Gaya is the answer that matches the Bihar-specific fact asked in the question. The Mahabodhi Temple is located in Bodh Gaya, which falls under the Gaya district of Bihar. Bodh Gaya is one of the most sacred Buddhist pilgrimage sites in the world, as it is the place where Siddhartha Gautama attained enlightenment under the Bodhi Tree. The Mahabodhi Temple was built by Emperor Ashoka in the 3rd century BCE and was later reconstructed in the 5th–6th century CE. UNESCO declared it a World Heritage Site in 2002. Nalanda district is home to the ruins of the ancient Nalanda University, which is also a UNESCO World Heritage Site, but the Mahabodhi Temple is not there. Vaishali is known as the birthplace of Lord Mahavira and an important site of Buddhist and Jain history, but the Mahabodhi Temple is not located there. Patna, the capital of Bihar, was the ancient city of Pataliputra but does not have the Mahabodhi Temple. The Bodhi Tree under which Buddha attained enlightenment is still present at Bodh Gaya. Bihar GK questions frequently place neighbouring districts, rivers, historical centres, personalities or government institutions together as distractors, so recognition of a familiar name alone is insufficient. The alternatives Nalanda, Vaishali, Patna may be valid Bihar-related terms, but they do not satisfy the complete relationship asked here.